Depressive Symptoms and Mortality Among US Adults

IMPORTANCE: Depression is a common mental health disorder in the US. Depressive symptoms have been associated with increased cardiovascular disease incidence and mortality, but studies have largely focused on narrow population subgroups. OBJECTIVE: To examine the association between depressive symptoms and mortality in a large, diverse, nationally representative sample of US adults, and to examine how lifestyle factors mediate this association. DESIGN, SETTING, AND PARTICIPANTS: This was a prospective cohort study of a nationally representative sample of US adults using National Health and Nutrition Examination Survey 2005 to 2018 data linked with the National Death Index through 2019 for adults aged 20 years and older. Data were analyzed between March 1 and May 26, 2023. MAIN OUTCOMES AND MEASURES: All-cause, cardiovascular disease, and ischemic heart disease mortality. Depressive symptoms were defined by Patient Health Questionnaire-9 scores and were categorized as none or minimal, mild, and moderate to severe. Secondarily, we assessed degree of mediation by lifestyle factors. RESULTS: A total of 23 694 participants were included (unweighted n = 11 862 male [weighted 49.8%]; mean [SE] age, 44.7 [0.24] years). Prevalences of mild and moderate to severe depression were 14.9% and 7.2%, respectively. For all-cause mortality, hazard ratios were 1.35 (95% CI, 1.07-1.72) for mild depressive symptoms vs none and 1.62 (95% CI, 1.24-2.12) for moderate to severe depressive symptoms vs none. The corresponding hazard ratios were 1.49 (95% CI, 1.11-2.00) and 1.79 (95% CI, 1.22-2.62) for cardiovascular disease mortality and 0.96 (95% CI, 0.58-1.60) and 2.21 (95% CI, 1.24-3.91) for ischemic heart disease mortality. The associations were largely consistent across subgroups. Approximately 11.0% to 16.1% of the associations between depression and mortality could be explained by lifestyle factors. Feeling tired or having little energy, poor appetite or overeating, and having little interest in doing things were independently associated with all-cause and cardiovascular disease mortality but not with ischemic heart disease mortality. CONCLUSIONS AND RELEVANCE: In this prospective cohort study of a nationally representative sample of US adults, there was a graded positive association between depressive symptoms and mortality. Public health efforts to improve awareness and treatment of depression and associated risk factors could support a comprehensive, nationwide strategy to reduce the burden of depression.